1. Field of the Invention
The present invention relates generally to a method and apparatus for transmitting and receiving data in a communication system. More particularly, the present invention relates to a method and apparatus for transmitting and receiving data using Relay Stations (RSs) in a Hybrid Division Duplex (HDD)-based communication system.
2. Description of the Related Art
FIG. 1 is a diagram illustrating data transmission and reception using RSs according to the conventional art.
Referring to FIG. 1, in an arbitrary cell 100, a Base Station (BS) 102 communicates with any of Mobile Station 1 (MS1) 108, MS2 110, MS3 112, MS4 114 and MS5 116 directly or via one of an RS1 104 and an RS2 106. The BS 102 and the RSs 104 and 106 use different subchannels.
The MS1 108 located in a boundary of the cell 100 and the MS5 116 located inside the cell 100 both communicate directly with the BS 102. That is, because the BS 102 is located a shorter distance from each of them as compared to the distance to either of RS1 104 or RS2 106, the MS1 108 and the MS5 117 communicate in synchronization with the BS 102 directly, without using an RS. In comparison, because of its distance from the BS 102 compared with its distance to an RS, the MS2 110 communicates with the BS 102 via its nearest RS1 104. Similarly, the MS3 112 and the MS4 114 also communicate with BS 102 via their nearest RS2 106.
Because of the different paths by which the MSs connect to the BS, the MSs have different synchronizations and an offset between the different synchronizations may occur. For example, a synchronization offset 135 occurs between first data 120 that the BS 102 has directly received from the MS1 108 and second data 130 that the BS 102 has received from the MS2 110 via the RS1 104. That is, in a period where the BS 102 performs Fast Fourier Transform (FFT) demodulation on the received first and second data 120 and 130, Cyclic Prefix (CP)-length phase shift occurs at arrival times of the data 120 and 130, causing Inter-Carrier Interference (ICI) 140.
In the foregoing conventional communication system, since the devices, such as BS and/or RS, to which an MS is connected, have different synchronizations, ICI interference may occur during received data demodulation at the BS, causing a decrease in the system performance.